Get this book only if you are really, really into catfishes. You know this may not be for you the moment you see words in the title that may be unfamiliar to you (aptations are characters that confer evolutionary fitness on an organism, and homoplasies are similarities in character states for reasons other than inheritance from a common ancestor). This book (it's actually Diogo's Ph.D. dissertation) contains very little that may interest aquarists, but it's interesting reading if you are interested in higher-level relationships of catfishes (i.e. how the different catfish families are related to each other). This is not the final word on catfish relationships, but it is certainly one of the first that is easily available. If the hefty price tag does not faze you and you intend to read this book without some background knowledge in phylogenetic systematics, then additional investment in a biological dictionary is probably necessary.